What effect does the conclusion of the text, focused on the attack of Charles Sumner, have on the development of the central ideas of the text?

Inferred you are referring to Charles Sumner former US senator.

It encourages sympathy

Explanation:

Remember, we are told Sumner spent three and a half years recovering from the beating resulting from the attack. Although he initially attacked someone, who's cousin later retaliated with physical attack against Sumner. This story of the attack is in line with the central idea of who is painted as the man- Charles Sumner, a fiece activist who got in anyone's way in making his views heard.